Asteroid Buzzes Earth in Close Shave: First Photos

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An asteroid the size of a tour bus zipped by Earth today (June
27) in a flyby so close that the space rock was nearer to the
planet than some satellites, giving skywatchers and astronomers a
tantalizing target for photos.

The space rock, called
asteroid 2011 MD, reached its closest point to Earth just
after 1 p.m. EDT (1700 GMT), when it crept within 7,500 miles
(12,000 km) of Earth before whipping away again like a slingshot.
The asteroid was flying over the southern Atlantic Ocean, off the
coast of Antarctica, at the time of its closest approach.

The asteroid was discovered just last week on June 22, but there
was never any risk of it impacting Earth, NASA scientists said.
Astronomers with the LINEAR near-Earth object survey in Socorro,
N.M., made the find. [ Video
of asteroid 2011 MD ]

The space rock is on the small side, with latest size estimates
ranging from 16 to 66 feet (5 to 20 meters) wide.

That means asteroid 2011 MD would likely be too small to survive
the fiery plunge through Earth's atmosphere, let alone reach the
surface, NASA scientists said.
Asteroids this size can be expected to buzz Earth with close
shaves about once every six years, they added.

The asteroid's close brush with Earth sent it off on a new
trajectory through the solar system. The space rock flew well
below geosynchronous satellites, which orbit 22,236 miles
(35,786 km) above Earth, but well above the 220-mile
(354-km) altitude of the International Space Station.

Amateur astronomer Efrain Morales Rivera of Aguadilla, Puerto
Rico, spotted the asteroid today just hours before its closest
approach. At that time, asteroid 2011 MD was a small and was
extremely dim, making it an extra challenge to spot, said Rivera,
who posted his photos on the website Spaceweather.com.

"But overall, [it was] well worth the grand effort and the
weather held off for this moment too," Rivera told SPACE.com in
an email. "Presently a tropical storm is upon us as I write
this."

A team of three skywatchers with the Remanzacco Observatory in
Italy used remote operated telescopes in Australia and New Mexico
to catch views of the asteroid. Two of the skywatchers, Ernesto
Guido and Giovanni Sostero, are based in Italy, while their
colleague Nick Howes is in the UK.

One of the trio's images, taken with the Faulkes Telescope South
in Siding Springs, Australia,show the asteroid in red, green and
blue wavelengths, while another using the New Mexico instrument
show the space rock as a streak of light on a starry
background.

"It was quite amazing watching it on Faulkes literally fly across
the screen," Howes told SPACE.com. "We had to move the telescope
four times just to keep up."

Another photo of asteroid 2011 MD, this one snapped by astronomer
Peter Birtwhistle of the Great Shefford Observatory in the United
Kingdom on June 23, revealed the space rock as little more than a
dim, moving point of light.

NASA's asteroid trackers

Don Yeomans, of NASA's Near-Earth Object Program Office at NASA's
Jet Propulsion Laboratory in Pasadena Calif., told SPACE.com that
astronomers hoped to take radar observations 2011 MD during the
asteroid's flyby. However, hopes were low for any detailed images
because of the space rock's small size, Yeomans added.[ Photos:
Asteroids in Deep Space ]

Only seasoned skywatchers with medium-sized telescopes were
expected to see the asteroid at all, NASA officials said.

When the asteroid was first discovered, the early reports
suggested that it would make its closest approach to Earth on
about 9:30 a.m. EDT (1330 GMT), more than three hours earlier
than the actual event. But that report was based on just two days
of observations, Yeomans said.

"The new improved orbit has 4 days of observations rather than
two, and the current Earth close approach time is now 1:00 pm EDT
on Monday," Yeomans said in an e-mail. "This time should be good
to a few minutes."

Earth's asteroid close shaves

Asteroid 2011 MD is the second space rock to zip extremely close
by Earth this year. The other object, called
asteroid 2011 CQ1, passed within 3,400 miles (5,471
kilometers) of Earth on Feb. 4, making it the closest known flyby
of an asteroid to date.

NASA scientists and other astronomers search for near-Earth space
rocks like 2011 MD as part of a program to identify potentially
hazardous asteroids that could threaten the planet.

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